Disclosed is a terminal controlling system and method for controlling multi-device. A method of operating a terminal controlling system according to the present disclosure includes: by a first terminal, detecting a second terminal and producing detection result information; by the first terminal, transmitting the detection result information to a first control device controlling the first terminal; by the first control device, making a request to a server device for information on the second terminal; by the first control device, making a request to a second control device controlling the second terminal for inter-terminal interworking, using the information on the second terminal received from the server device; by the first control device, receiving a response to the inter-terminal interworking request from the second control device; and by the first terminal, communicating with the second terminal based on the response received from the first control device.